The research, published in the journal Nature, constructed the human liver tissue using a combination of three cell types: induced pluripotent stem cells (iPS cells), human umbilical cord blood stem cells, and bone marrow mesenchymal stem cells. The liver cells were induced to form from the iPS cells, while the other cells were used to form support tissue including cells for blood vessels. In the laboratory, the cells organized themselves into pieces of tissue, termed “liver buds”. When transplanted into mice, the “liver buds” showed some specific liver function, and also hooked into the circulatory system, allowing the liver tissue to survive and continue growing. The functional human liver tissue was also able to rescue mice from liver failure.

It’s still early in the study and development of iPS cell-derived tissues and organs, and the mice will be observed for some time to come to observe whether iPS cells, since they behave like embryonic stem cells, create tumors in the animals. Still, it’s a significant step forward for potential use of iPS tissues in laboratory studies, and a novel way to produce organ rudiments.